Copolymer rubber, and foamed article, vulcanized rubber, profile extrusion molded rubber and hose for water comprising said copolymer rubber

Abstract

There is provided an ethylene-α-olefin-non-conjugated diene copolymer rubber satisfying the following requirements (1) to (4): (1) a ratio of a Z-average molecular chain length (Az) measured according to a gel permeation chromatography to a number average molecular chain length (An), Az/An, of the ethylene-α-olefin-non-conjugated diene copolymer rubber is from 20 to 30, (2) a ratio of a weight average molecular chain length (Aw), which is an index of a molecular weight distribution, to the number average molecular chain length (An), Aw/An, of the ethylene-α-olefin-non-conjugated diene copolymer rubber is more than 5, (3) a unimodal or bimodal molecular weight distribution structure having a molecular chain length component, which component is present in a maximum amount in a range of 3.8<Log Aw<4.5, exists in the ethylene-α-olefin-non-conjugated diene copolymer rubber, and (4) a viscosity (ML 1+4 , 121° C.) of the ethylene-α-olefin-non-conjugated diene copolymer rubber measured with a ML viscometer is more than 60 and less than 160.

1. An ethylene-α-olefin-non-conjugated diene copolymer rubber satisfying the following requirements (1) to (4):
 (1) a ratio of a Z-average molecular chain length (Az) measured according to a gel permeation chromatography to a number average molecular chain length (An), Az/An, of the ethylene-α-olefin-non-conjugated diene copolymer rubber is from 20 to 30, 
 (2) a ratio of a weight average molecular chain length (Aw), which is an index of a molecular weight distribution, to the number average molecular chain length (An), Aw/An, of the ethylene-α-olefin-non-conjugated diene copolymer rubber is more than 5, 
 (3) a unimodal or bimodal molecular weight distribution structure having a molecular chain length component, which component is present in a maximum amount in a range of 3.8<Log Aw<4.5, exists in the ethylene-α-olefin-non-conjugated diene copolymer rubber, and 
 (4) a viscosity (ML 1+4 , 121° C.) of the ethylene-α-olefin-non-conjugated diene copolymer rubber measured with a ML viscometer is more than 60 and less than 160. 
 
     
     
       2. The ethylene-α-olefin-non-conjugated diene copolymer rubber according to  claim 1 , wherein a ratio by weight of an ethylene unit to an α-olefin unit contained in said copolymer rubber is from 80/20 to 45/55, and a content of a non-conjugated diene unit contained therein is from 5 to 35 in an iodine value. 
     
     
       3. The ethylene-α-olefin-non-conjugated diene copolymer rubber according to  claim 1 , wherein the non-conjugated diene contains 5-ethylidene-2-norbornene or a combination thereof with dicyclopentadiene, 5-vinyl-2-norbornene or norbornadiene. 
     
     
       4. The ethylene-α-olefin-non-conjugated diene copolymer rubber according to  claim 1 , wherein a ratio of the Z-average molecular chain length (Az) to a residual compressive stress ratio, Az/residual compressive stress ratio, is not more than 2700, wherein the residual compressive stress ratio is measured by a method comprising the steps of:
 (i) compressing said copolymer rubber at 80° C. by 50%, 
 (ii) after 0.01 second, measuring its stress (S 0.01 ), 
 (iii) after 100 seconds, measuring its stress (S 100 ), and 
 (iv) calculating a formula, residual compressive stress ratio=S 100 /S 0.01 . 
 
     
     
       5. A foamed article comprising a copolymer rubber mentioned in  claim 1 . 
     
     
       6. A process for producing a foamed article, which comprises the step of foaming under vulcanization a composition containing:
 (i) 100 parts by weight of an ethylene-α-olefin-non-conjugated diene copolymer rubber mentioned in  claim 1 , 
 (ii) from 50 to 200 parts by weight of carbon black, 
 (iii) from 30 to 150 parts by weight of a softening agent, and 
 (iv) from 2 to 15 weight of a foaming agent. 
 
     
     
       7. Vulcanized rubber comprising a copolymer rubber mentioned in  claim 1 . 
     
     
       8. A process for producing vulcanized rubber, which comprises the step of vulcanizing a composition containing:
 (i) 100 parts by weight of an ethylene-α-olefin-non-conjugated diene copolymer rubber mentioned in  claim 1 , 
 (ii) from 30 to 250 parts by weight of carbon black, and 
 (iii) from 30 to 200 parts by weight of a softening agent. 
 
     
     
       9. Profile extrusion molded rubber comprising a copolymer rubber mentioned in  claim 1 . 
     
     
       10. A process for producing profile extrusion molded rubber, which comprises the step of vulcanizing a composition containing:
 (i) 100 parts by weight of an ethylene-α-olefin-non-conjugated diene copolymer rubber mentioned in  claim 1 , 
 (ii) from 30 to 250 parts by weight of carbon black, and 
 (iii) from 30 to 200 parts by weight of a softening agent. 
 
     
     
       11. A hose for water comprising a copolymer rubber mentioned in  claim 1 . 
     
     
       12. A process for producing a hose for water, which comprises the step of vulcanizing a composition containing:
 (i) 100 parts by weight of an ethylene-α-olefin-non-conjugated diene copolymer rubber mentioned in  claim 1 , 
 (ii) from 30 to 250 parts by weight of carbon black, and 
 (iii) from 30 to 200 parts by weight of a softening agent.